A coating die is used to apply a thin layer of liquid material (e.g., thermoplastic or solvent based) to a support substrate such as a sheet or film. The most common coating process is to provide a continuous layer of coated material on the substrate by having a continuous stream of material applied to the moving substrate.
A coating die includes at least an inlet for receiving the material to be coated, a manifold to distribute the material across the width of the coating die, and an outlet through which the material exits the die. The exact configuration of the die will vary depending on the material being coated, the desired coating properties (i.e., allowable pressure drop, flow rate, etc.), the desired coating width, etc. If a coating line or facility interchangeably runs numerous types of coatings, then the facility needs to have an inventory of different dies. Because a coating die is a very expensive piece of capital equipment, large amounts of money are tied up in the various dies.
Many facilities have at least one back-up coating die for occasions when the die being used gets damaged. Again however, the facility needs to have an inventory of back-up dies.